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  • 1
    ISSN: 1542-474X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Aim: This study investigated the value of epicardial mapping immediately before CABG in the differentiation of hibernating from scarred myocardium in correlation to the noninvasive gold standard 18F-FDG PET.Methods and Results: In 35 patients with CAD, myocardial perfusion (99mTc-Tetrofosmin-SPECT), viability (18F-FDG-PET), and function (LVangiography) were assessed before CABG. 102 bipolar epicardial electrograms per patient (n = 3570 electrograms) were recorded simultaneously with a ventricular jacket array. Based on the scintigraphic and LV angiographic data at the site of each electrode with good myocardial contact (n = 1963), segments (n = 492, 14.1 ± 5.6 per patient; mean ± SD) were classified into three groups: hibernating (n = 139), scarred (n = 104), and control (n = 249). Regional mean bipolar voltage values were calculated for Receiver Operating Characteristic (ROC) analysis. Mean bipolar voltage was significantly lower in scarred when compared to hibernating myocardium. ROC curve analysis (area under the curve of O.92 ± 0.47, mean ± SE) for mean bipolar voltage to discriminate between hibernating and scarred myocardium revealed a sensitivity of 94% with a specificity of 83% at a cut-off value of 8.75 mV.Conclusion: Hibernating myocardium can be differentiated correctly from scarred myocardium by direct epicardial mapping. In the future, hibernating myocardium may be detectable by body surface mapping techniques using inverse solutions. A.N.E. 2002;7(4):349–356
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: 3-[123I]Iodo-L-α-methyl tyrosine (123I-IMT) is used for diagnosis and monitoring of brain tumours by means of single-photon emission tomography. As recently shown, 123I-IMT is predominantly mediated into rat C6 glioma cells by sodium-independent system L for large neutral amino acids. Until now, 123I-IMT transport in non-neoplastic glial cells has not been examined. Therefore, the aim of this study was to examine the cellular pathways and precise transport kinetics of 123I-IMT uptake into astrocytes of neonatal rats. In particular sodium-independent 123I-IMT transport into neonatal astrocytes was compared with sodium-independent 123I-IMT uptake into neoplastic rat C6 glioma cells.Competitive inhibition experiments showed that 123I-IMT is exclusively transported via sodium-independent system L into the neonatal astrocytes (92%). Kinetic analysis of sodium-independent 123I-IMT uptake into neonatal astrocytes and into C6 glioma cells revealed apparent Michaelis constants KM = 13.9 ± 0.5 µm and KM = 33.9 ± 4.1 µm, respectively, which are in the same range of KM values as those recently determined for amino acid transport into neoplastic and non-neoplastic glial cells. Indeed, the KM values in the micromolar range correspond to the expression of the LAT-1 subunit of system L both in the neonatal astrocytes and in C6 glioma cells. However, sodium-independent maximum transport velocities (Vmax) differed significantly between neonatal astrocytes and C6 glioma cells (11.1 ± 0.3 and 39.9 ± 3.3 nmol/mg protein/10 min, respectively).
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    ISSN: 1468-2982
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The case of a 69-year-old woman with chronic paroxysmal hemicrania (CPH) is presented in whom cerebral perfusion was investigated using the flow tracer 99mTc-hexamethyl propylenamino oxime (HMPAO) and single photon emission tomography (SPECT). There was a bilateral hypoperfusion in the fronto-parietal region between attacks-without medication as well as under effective treatment with verapamil. During an attack, however, SPECT investigation showed a normal cerebral perfusion. Further investigation is required to find out whether these SPECT findings are due to primary alterations of brain perfusion in CPH or are only of epiphenomenological nature. The observed effectiveness of verapamil in the prophylactic treatment of CPH should be verified in a greater number of patients.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    ISSN: 1468-2982
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Acetazolamide, a carbonic anhydrase inhibitor, has proved to be useful in the assessment of “vasodilatory capacity” in cerebrovascular disease. To obtain further information on the nature of interictal low-flow regions in migraine, we reinvestigated 20 asymptomatic patients suffering from migraine with aura (n = 15) or without aura (n = 5) and who had either minor (n = 12) or marked (n = 8) regional hypoperfusion when examined in a previous 99mTc-HMPAO SPECT investigation. These patients received acetazolamide IV prior to tracer application. In 14/20 cases regional hypoperfusion resolved. Three patients with migraine with aura had less pronounced regional hypoperfusion compared to baseline. No change in baseline hypoperfusion was detectable in three older patients. No further decreases in flow were measured. In contrast to patients with cerebrovascular ischemia, in whom acetazolamide usually enhances low-flow regions, vasodilatory capacity appears intact in most migraine patients with interictal regional hypoperfusion. Thus, the “acetazolamide test” might be useful in the differential diagnosis of migraine with aura from transient cerebrovascular ischemia.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Neurosurgical review 10 (1987), S. 19-22 
    ISSN: 1437-2320
    Schlagwort(e): Brain death ; cerebral blood flow (CBF) ; children ; lipophilic radiopharmacons
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Brain imaging with radiolabeled amines,123I-IMP and99mTc-HM-PAO, is a rapid, safe, and specific bedside test for confirming brain death in the absence of cerebral blood flow. Therapeutic phenobarbital or thiopental levels do not interfere with the cerebral penetration ability of the lipophilic radiopharmacons.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    ISSN: 1437-2320
    Schlagwort(e): Amino acids ; positron emission tomography (PET) ; protein ; rat brain ; uptake kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Because the amino acids11C L-leucine,11C L-methionine, and11C D-methionine are used for examinations of brain tumors with positron emission tomography (PET), the uptake of the corresponding14C substances and their incorporation into protein was studied in the rat brain. The uptake of all three substances from the plasma, across the bloodbrain barrier, and into the brain took place quite quickly; return to the plasma seemed negligible. Incorporation into protein took place much more slowly.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    ISSN: 1437-2320
    Schlagwort(e): Desmoplastic infantile ganglioglioma ; iodine 123-α-methyl tyrosine ; SPECT
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Amino acid uptake is higher in high-grade than in low-grade gliomas; this is the rationale for using radioactively labelled amino acids for the non-invasive grading of brain neoplasms. We present a 14-year-old boy with a low-grade desmoplastic infantile ganglioglioma (DIG) that exhibited marked contrast enhancement on magnetic resonance imaging (MRI), but no signs of infiltration and only minimal surrounding edema. In this benign neoplasm the relative uptake of the radioactively labelled amino acid I-123-α-methyl tyrosine (IMT), determined using single-photon emission computed tomography (SPECT), was 3.24; it was considerably higher than that of eleven other pretherapeutic low-grade gliomas where it ranged from 1.06 to 1.94 and also markedly above the average value of 2.37 found in 20 high-grade gliomas. This case report illustrates that results from emission tomography with radioactively labelled amino acids must be interpreted with caution, particularly when rare tumor entities are considered in view of uncommon clinical or radiological findings.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Human genetics 〈Berlin〉 51 (1979), S. 93-97 
    ISSN: 1432-1203
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The frequency of sister chromatid exchanges (SCEs) in the centromere of chromosomes involved in a whole-arm translocation t(1;19) was evaluated in altogether 911 metaphases of translocation carriers (n=5) and of normal controls (n=6). Comparison of the two groups reveals no significant differences in the SCE rate (x 2=3.06, n f =1). The question as to whether the possible increase of the SCE rate at the translocation point could be detected by light microscopy is discussed. Parameters included in the discussion are the ratio of the SCE frequency at the translocation point to the SCE frequency at any of the possible breakage points in the centromeric region and the number of possible breakage points in the centromeric region.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    ISSN: 1619-7089
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Regional extravascular lung water (rELW) and blood volume (rBV) in five controls and 14 patients with congestive heart failure (CHF) were measured by constant infusion of H2 15O and inhalation of 11CO using positron emission tomography (PET). The analysis of 18 regions per patient revealed a relatively homogenous level of rELW in the controls (x=0.11±0.02 g/cc; range, 0.08–0.21), whereas this increased in patients with CHF (0.17±0.02 g/cc; range, 0.10–0.51). The rBV was 0.21±0.02 g/cc in the controls and 0.17±0.02 g/cc in patients with CHF. A good correlation was found between the severity of chronic heart failure (according to the grading of the New York Heart Association) and mean extravascular lung water (ELW) (r=0.69), as well as between CHF and the ratio rELW/rBV (r=0.87); however, the correlation to hemodynamic data was less satisfactory (cardiac index, r=0.45; pulmonary capillary wedge pressure, r=0.47; ejection fraction, r=0.60). In supine controls, a progressive decrease in regional blood volume from the basal to the apical regions was observed, whereas the differences in ELW were only small. In patients with chronic heart failure, ELW in the basal parts was markedly increased, whereas in the apical regions, only minor deviations from the controls were observed. In the basal regions of these patients, the blood volume was reduced by about 30%. Instead of the normal basoapical gradient of blood volume, these patients showed a rather flat distribution. Radiographic findings of pulmonary edema generally appeared together with an ELW level of greater than 0.14 g/cc. We conclude that the amount and distribution of fluid in pulmonary congestion can be noninvasively assessed by PET.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    ISSN: 1619-7089
    Schlagwort(e): 15O ; extravascular water ; mean transit time ; tracer kinetics ; positron emission tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Steady state tracer measurements with short-lived isotopes allow the determination of dynamic and static physiological functions and parameters. Both types of measurements are affected by the gradient effects which result from the decay of the tracer through the volume observed. Using 15O-labelled compounds and positron emission tomography (PET), dynamic functions like flow are quite sensitive to variations in extraction fraction and distribution coefficient. In the operational equation for the determination of distribution volumes the gradient effect can be reduced to correction terms which are governed by the mean transit time of the tracer through the observed volume. Because mean transit times can be measured independently they allow a reasonable correction of gradient effects in distribution volume determinations, even if deviations of extraction fraction and distribution coefficient from unity must be considered.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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